Adenosine and Cardiac Aging

Basal and s-adrenergic-induced interstitial adenosine levels are significantly higher in the aged compared to the young adult myocardium. This results in a greater manifestation of the antiadrenergic action of adenosine reducing s-adrenergic responsiveness. Results suggest that despite similar adenosine production by young adult and aged myocardium, elevated basal interstitial adenosine levels in aged myocardium result from depressed in vivo activity of adenosine kinase coupled to a reduced inward adenosine transport. With s-adrenergic stimulation, adenosine production is greater in the young compared to aged heart. However, efficient recycling of adenosine in the young heart minimizes the enhanced adenosine release. This results in a net adenosine release which is still greater in the aged heart.